I love washing my E93 (non M), for the same reasons. The E9x is a stunning design, and even more so in M-clothing.

In fact I was going to wash it today but the weather was a bit chilly and windy so I decided to wait until later next week when it's warmer and no rain in the forecast. I love using the griots products and I do cringe though trying to get the brake dust off my M359 wheels in black. I think each time I get a few more scratches into the wheels no matter how much soap and water I try to use.

What I hate more though is after my car is finally all clean, I can't stand when lights turn red on me and I need to apply the brakes to stop, getting the nice and fresh wheels coated in brake dust all over again!!! Stupid brake dust.. lol